When the 375 Ruger first came out, I called Dave Kiff at Pacific Tool and Gauge. He already had a reamer made up for someone else.
More recently I called Redding to ask if they had a 338/375 Ruger full length sizing and seating die set. They did and it was $160. I didn't ask if they had the 7mm version but I'll bet they do.
For what it is worth, I am getting 3275 with a 150 nos E-tip in a 24" 7 Rem mag. Moly and RL-17 made the difference. I have to wonder what a 160 could do with a 26" barrel and either RL-17 or the soon to hit the market Power Pro 4000 MR and moly. Might do what you want with little cost or effort.
FYI the Power Pro 4000 MR is made by the same company that made RL-17, Nitrochemie. It is going to have similar characteristics with a long burning curve. Graf and Sons has it on back order. According to Alliant's representative Ben Amonette it will be out there soon:
"We hope the first of the Power Pro series, 300MP (magnum pistol) and 4000MR (magnum rifle) will be released this spring. Later in the year we hope to have "Varmint", 2000MR (medium rifle), 3000LR (large rifle) ready to go. More information will be available closer to release time.Thanks for your note."
I will be trying 4000 in the 24" 7 mag and 30" 7 rem mag as soon as it is in my hands. I'll report my findings here.